(1) Field of the Invention
This invention relates to a transition metal compound, a coordinative compound, a catalyst for polymerization of an olefin comprising the transition metal compound, and a process for polymerizing an olefin using the catalyst.
(2) Description of the Related Art
It is known that a homogeneous catalyst comprising a combination of a transition metal compound containing a metal of group 4 of the periodic table and having a cyclopentadienyl derivative as a ligand with an aluminoxane exhibits a high activity for polymerization of olefins and is used therefor (for example, Japanese Unexamined Patent Publication [hereinafter abbreviated to “JP-A”] No. S58-19399). Catalysts comprising an organometallic complex having a cyclopentadienyl structure a non-ligand, which include the above-mentioned homogeneous transition metal catalyst, are known as giving a polyolefin having a narrow molecular weight distribution and having a uniform distribution in composition over the polymer.
In recent years, to provide an improved homogeneous catalyst for polymerization of olefins, extensive researches have been made on homogeneous catalysts comprising an organometallic complex having a ligand other than that having a cyclopentadienyl structure, i.e., a ligand containing a heteroatom. For example, as for catalysts for polymerization of olefins comprising an organometallic complex of a transition metal compound with a ligand containing a nitrogen atom, JP-A H8-176217 and JP-A H8-245713 disclose a catalyst for polymerization of an olefin comprising a titanium amide compound containing a titanium metal with a dialkylamine as a ligand. JP-A H10-298216 discloses a catalyst for polymerization of an olefin comprising a transition metal amide compound with a crosslinkable aromatic amine compound as a ligand.
Catalysts for polymerization of olefins comprising an organometallic complex with a ligand comprising a nitrogen atom have also been widely studied from a scientific point of view. Living polymerization of 1-hexene using a catalyst system comprising a diamide complex represented by the formula: [ArN(CH2)3NAr]TiMe2, and B(C6F5)3 is described in D. H. McConville et al, J. Am. Chem. Soc., vol. 118, p.10008 (1996). Living polymerization of 1-hexene using a catalyst system comprising a diamido complex with a tridentate ligand, represented by the formula: [(t-BuN-ortho-C6H4)2O]ZrMe2 and B(C6F5)3, is described in R. R. Schrock et al, J. Am. Chem. Soc., vol. 119, p.3830 (1997). Further, synthesis of a transition metal compound containing a metal of group 4 with a ligand having a bis(borylamide) structure such as [Mes2BNCH2CH2NBMes2]2− and its catalytic activity for polymerization of ethylene are described in Organometallics, vol. 15, p562 (1996) and Organometallics, vol. 17, p308 (1998).
Recently, it has been reported that a catalyst comprising a bidentate ligand-containing diimine chelate-type nickel complex gives a polyolefin having a structure with many branches introduced therein, which is distinct from a structure of the conventional polyolefins produced by using a metallocene catalyst (for example, WO96/23010). Further, it has been reported that a catalyst comprising an aldimine chelate-type group 4 transition metal complex exhibits greatly enhanced activity for polymerization of an olefin (for example, EP 874,005 (1998), and J. Am. Chem. Soc., vol. 123, p6847 (2001)).